Effects of functional pasta ingredients on different gut microbiota as revealed by TIM-2 in vitro model of the proximal colon

Diet-related modulation of gut microbiota and its metabolic activity represents an intriguing research context, particularly in the case of disorders related to imbalances in gut microbial communities. We here explored the effects of Bacillus coagulans GBI-30, 6086 (BC30), β-glucans, and innovative whole-grain pastas, with or without these functional ingredients, on gut microbiota from three groups of children, presenting different susceptibility to type 1 diabetes, by using the well-controlled TNO in vitro model of the proximal colon (TIM-2). Short- and branched-chain fatty acids production and microbiota composition were assessed by means of gas chromatography and 16S rRNA gene profiling, respectively. In most cases, in vitro dietary interventions caused microbiota-dependent modulations as a result of intergroup variability, but also specific changes in microbial groups were shared between the three microbiotas, highlighting specific diet-microbial taxa connections.

Growth, biogenic amine production and tyrDC transcription of Enterococcus faecalis in synthetic medium containing defined amino acid concentrations

AIMS

The tyraminogenic potential of the strains Enterococcus faecalis EF37 and ATCC 29212 was investigated in a synthetic medium containing defined amounts of tyrosine and phenylalanine at different temperatures.

METHODS AND RESULTS

Enterococci growth and the production of biogenic amines (BA) were evaluated in relation to their pre-growth in medium containing tyrosine. Significant differences between the two strains were evidenced at metabolic level. Both the pre-adapted strains grew faster in all the tested conditions, independently of the presence of the precursor. Temperatures of 30 and 40°C positively affected the growth parameters. The tyrosine decarboxylase (tyrDC) activity of the strain EF37 was positively affected by pre-adaptation, while ATCC 29212 showed a faster and higher tyramine accumulation with not-adapted cells. The expression analysis of the gene tyrDC confirmed the influence of the growth conditions on gene transcription.

CONCLUSIONS

The small differences found between the two strains in the maximum transcript level reached rapidly after the inoculum and the different behaviour in the tyramine accumulation suggested the possible involvement of complex regulation mechanisms on the tyrDC or on the membrane transport systems, which could affect the different BA accumulation trend.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study gives deeper insight into the metabolic regulation of tyrDC activity of enterococci.

Genetic and phenotypic strain heterogeneity within a natural population of Oenococcus oeni from Amarone wine

AIMS

To investigate the Oenococcus oeni population occurring during spontaneous malolactic fermentation (MLF) of Amarone wine, a peculiar and hostile environment for malolactic bacteria.

METHODS AND RESULTS

Pulsed-field gel electrophoresis (PFGE) analysis showed a high level of genetic heterogeneity within the O. oeni population involved in MLF throughout an industrial vinification of Amarone wine. The 13 strains with distinct PFGE profile displayed different capability to hydrolyse esters and glycosides, as well as great variability to growth under stress parameters, such as high ethanol content (15% v/v), low pH (3·0) and temperature (15°C), and presence of SO(2). Moreover, polymorphism in the gene sacB involved in exopolysaccharide production was observed among the strains. The strains showed differences to convert l-malic acid into l-lactic acid in wine.

CONCLUSIONS

The occurrence of spontaneous MLF in stressful ecosystems such as Amarone wine is related to the heterogeneity of O. oeni community; biodiversity indexes and strain evolution analyses suggested that its success depends on its initial strain evenness.

SIGNIFICANCE AND IMPACT OF THE STUDY

Remarkable intraspecies complexity within the O. oeni natural population could explain the great versatility of this species as key of successful adaptation to harsh winemaking conditions.

Detection of Staphylococcus aureus and enterotoxin genotype diversity in Monte Veronese, a Protected Designation of Origin Italian cheese

AIMS

To evaluate the risk associated with the load and enterotoxigenicity of Staphylococcus aureus in Monte Veronese, a PDO (Protected Designation of Origin) cheese of the Lessinia area (Verona, Italy).

METHODS AND RESULTS

Staphylococcus aureus was quantified by a conventional culture method and by a nucA targeted real-time PCR assay developed in this study. Staphylococcus aureus numbers in cheese were higher than the limit tolerated by the Italian food legislation in 78% instances, according to both detection methods. Multiplex PCR tests for 17 Staph. aureus enterotoxin (SE) genes were applied to nucleic acids extracted from curds, cheeses and Staph. aureus isolates. The SE gene diversity appeared reduced after ripening. The gene encoding SED was found most frequently in dairy samples and the enterotoxin genes ser, sed, seg and sem predominated in the isolates.

CONCLUSIONS

The occurrence of enterotoxigenic Staph. aureus strains with complex SE genotypes in this PDO cheese at numbers often exceeding the Italian tolerance threshold represents an important risk factor.

SIGNIFICANCE AND IMPACT OF THE STUDY

The high frequency of contamination of Monte Veronese PDO cheese and, expectedly, similar typical productions from raw milk, by enterotoxigenic Staph. aureus imposes a tighter hygienic control in the earlier manufacturing phases.

Characterization of yeasts involved in the ripening of Pecorino Crotonese cheese

The aims of this work were to identify and characterize for some important technological properties the yeast species present throughout the ripening process of Pecorino Crotonese, a traditional cheese produced in a well defined area of Southern Italy. In particular, the strain technological properties considered include fermentation/assimilation of galactose and lactose, assimilation of lactate and citrate in the presence of different NaCl concentrations, hydrolysis of butter fat, skim milk, gelatine and casein, production of brown pigments in cheese agar and ability to produce biogenic amines. High yeast levels were recorded in cheese samples already after 5 h of brining (about 5 log cfu/g) and these concentration remained constant during ripening. The yeast isolates belonged to restrict number of yeast species. While Kluyveromyces lactis and Saccharomyces cerevisiae were isolated prevalently in the first stages of Pecorino Crotonese production, Yarrowia lipolytica and Debaryomyces hansenii dominated during the later stages of maturation. Otherwise, the latter two were very NaCl resistant species. In fact, D. hansenii strains conserved the ability to assimilate lactose and galactose in the presence of 10% NaCl, while almost all the strains of Y. lipolytica isolated assimilated citrate and lactate up to 7.5% NaCl. Y. lipolytica isolates evidenced also the highest proteolytic and lipolytic activities and the capability to catabolize tyrosine producing brown pigment. In addition they resulted in the highest aminobiogenic potential decarboxylating ornithine, phenylalanine, tyrosine and lysine. However, they were not able to produce histamine, biogenic amine produced by three strains of D. hansenii.

Reclassification of Lactobacillus thermotolerans Niamsup et al. 2003 as a later synonym of Lactobacillus ingluviei Baele et al. 2003

The relatedness of the speciesLactobacillus ingluvieiandLactobacillus thermotoleranswas investigated by comparing partial sequences of the 16S rRNA gene (99·9 % similarity over 1504 bp), thehsp60gene (98·8 % similarity over 954 bp) and therecAgene (98·5 % similarity over 452 bp) and by determining DNA–DNA binding levels (79±3 %) and genomic DNA G+C contents (50 and 49 mol%, respectively). These data, in addition to their similar biochemical characteristics, suggest that the two taxa constitute a single species. According to Rules 38 and 42 of theBacteriological Code, they should be united under the nameLactobacillus ingluviei, with the nameLactobacillus thermotoleransas a later heterotypic synonym.

Identification of probiotic microorganisms in South African products using PCR-based DGGE analysis

Probiotic microorganisms in commercial yoghurts and other food products are currently identified by traditional methods such as growth on selective media, morphological and biochemical characteristics. In this study, PCR-based DGGE analysis was used for the rapid and accurate identification of probiotic microorganisms from South African yoghurts and lyophilized preparations in capsule and tablet form. To identify the microorganisms present in these products, the DGGE profiles obtained were compared to two reference markers (A and B) composed of five lactobacilli and seven Bifidobacterium species, respectively. The results obtained were confirmed by species-specific PCR, as well as sequence analyses of unknown bands not present in the reference markers. It was found that only 54.5% of the probiotic yoghurts contained the microorganisms stated on the label compared to only a third (33.3%) of the lyophilized probiotic products. Some Bifidobacterium species were incorrectly identified and various microorganisms were detected that were not listed on the label. Sequence analyses confirmed the presence of Streptococcus spp. other than the yoghurt starter, Streptococcus thermophilus, in some of these products and in some instances label information was vague and non-scientific. PCR-based DGGE analyses proved to be a valuable culture-independent approach for the rapid and specific identification of the microbial species present in South African probiotic products.

Rapid identification and differentiation of Saccharomyces cerevisiae, Saccharomyces bayanus and their hybrids by multiplex PCR

AIMS

To develop a multiplex PCR assay for the specific identification and differentiation of Saccharomyces cerevisiae, S. bayanus and their hybrids.

METHODS AND RESULTS

Two sets of primers with sequences complementary to the region YBR033w were used. A single amplicon of 1710 bp or 329 bp was obtained with species S. cerevisiae and S. bayanus, respectively, while the presence of both bands was observed in S. pastorianus because of its hybrid nature. Both amplification products were also obtained after amplification from DNA of several laboratory S. cerevisiae x S. bayanus hybrid strains.

CONCLUSIONS

Multiplex PCR was optimized for the rapid and reliable identification of S. cerevisiae, S. bayanus and their hybrids.

SIGNIFICANCE AND IMPACT OF THE STUDY

The procedure may be used for routine detection of the most common Saccharomyces sensu stricto yeasts involved in industrial fermentation processes, overcoming the problems of conventional techniques.

Differentiation of Lactobacillus plantarum, L. pentosus and L. paraplantarum species by RAPD-PCR and AFLP

Two high-resolution genotypic techniques (RAPD-PCR and AFLP) were evaluated for their possibility to discriminate the species Lactobacillus plantarum, Lactobacillus pentosus and Lactobacillus paraplantarum and to type these taxa at the infra-species level. In total 23 strains of L. plantarum, three strains of L. pentosus, two strains of L. paraplantarum and two related strains for which the species assignment was not clear, were studied. For RAPD-PCR, suitable oligonucleotides and amplification conditions were selected and tested. For AFLP, a double digest of total genomic DNA was used and a subset of restriction fragments was selectively amplified and visualised using different primer combinations. Both methodologies generated, species-specific electrophoretic profiles. Moreover, the presence of distinct subgroups was revealed within the species L. plantarum.

Comparative sequence analysis of a recA gene fragment brings new evidence for a change in the taxonomy of the Lactobacillus casei group

The taxonomic positions of species of the Lactobacillus casei group have been evaluated by sequencing and phylogenetic analysis of a 277 bp recA gene fragment. High sequence similarity between strain ATCC 393T, currently designated as the type strain of L. casei, and the type strain of Lactobacillus zeae, LMG 17315T, has been established, while L. casei ATCC 334 and Lactobacillus paracasei NCDO 151T form a single phylogenetic group. The taxonomic status of species and strains at issue is discussed.

Rapid identification of Enterococcus durans and Enterococcus hirae by PCR with primers targeted to the ddl genes

Species-specific PCR assays with primers targeted to D-alanine:D-alanine ligase (ddl) encoding genes were developed for the identification of Enterococcus durans and E. hirae. The specificity of the primers was validated in a multiplex PCR on well characterised E. durans (n=30) and E. hirae (n=16) strains, all of which were identified correctly. This PCR procedure offers a reliable and rapid alternative to conventional phenotypic methods for speciation of these enterococci of growing clinical importance.

Differentiation of Lactobacillus plantarum, L. pentosus, and L. paraplantarum by recA gene sequence analysis and multiplex PCR assay with recA gene-derived primers

In this study, we succeeded in differentiating Lactobacillus plantarum, Lactobacillus pentosus, and Lactobacillus paraplantarum by means of recA gene sequence comparison. Short homologous regions of about 360 bp were amplified by PCR with degenerate consensus primers, sequenced, and analyzed, and 322 bp were considered for the inference of phylogenetic trees. Phylograms, obtained by parsimony, maximum likelihood, and analysis of data matrices with the neighbor-joining model, were coherent and clearly separated the three species. The validity of the recA gene and RecA protein as phylogenetic markers is discussed. Based on the same sequences, species-specific primers were designed, and a multiplex PCR protocol for the simultaneous distinction of these bacteria was optimized. The sizes of the amplicons were 318 bp for L. plantarum, 218 bp for L. pentosus, and 107 bp for L. paraplantarum. This strategy permitted the unambiguous identification of strains belonging to L. plantarum, L. pentosus, and L. paraplantarum in a single reaction, indicating its applicability to the speciation of isolates of the L. plantarum group.

Rapid detection of viable yeasts and bacteria in wine by flow cytometry

The potential of using flow cytometry (FCM) in combination with fluorescent dyes for rapidly estimating counts of yeasts and malolactic bacteria in laboratory media and wines was examined. In general, there was a good correlation (regression coefficient, 0.94) between viable counts of yeasts determined by FCM and by standard plate assay. The FCM detection limit of yeasts in YPDE medium and in Pinot noir must was 10(3) cells/ml. The lowest bacterial concentration detected by FCM was 10(4) cells/ml. When yeast and malolactic bacteria populations were simultaneously analysed in wine by FCM without any previous sample treatment, difficulties were encountered in the count of bacterial cells due to their size, which is similar to natural debries present in wine. However, after the optimisation of the sample preparation, the technique appeared promising in determining the presence of such microorganisms in wine with one single measurement. Because it is rapid and easy to use, flow cytometry can be considered a useful method for microbiological quality control in wineries and for the investigation of the growth dynamics of microorganisms in wine.

Phenotypic and genetic diversity of enterococci isolated from Italian cheeses

In the present study, 124 enterococcal strains, isolated from traditional Italian cow, goat and buffalo cheeses, were characterized using phenotypic features and randomly amplified polymorphic DNA polymerase chain reaction (RAPD-PCR). The RAPD-PCR profiles obtained with four primers and five different amplification conditions were compared by numerical analysis and allowed an inter- and intraspecific differentiation of the isolates. Whole cell protein analysis by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was used as a reference method for species identification. The strains were identified as Enterococcus faecalis (82 strains), E. faecium (27 strains), E. durans (nine strains), E. gallinarum (four strains) and E. hirae (two strains). Species recognition by means of RAPD-PCR was in agreement with the SDS-PAGE results except for eight strains of E. faecium that clustered in separated groups. On the other hand, phenotypic identification based on carbohydrate fermentation profiles, using the rapid ID 32 STREP galleries, gave different results from SDS-PAGE in 12.1% of the cases. The majority of the strains had weak acidifying and proteolytic activities in milk. One E. faecium strain showed vanA (vancomycin resistance) genotype while four strains showed a beta-haemolytic reaction on human blood. Several strains showed antagonistic activity towards indicator strains of Listeria innocua, Clostridium tyrobutyricam and Propionibacterium freudenreichii subsp. shermanii.

Identification by 16S-23S rDNA intergenic region amplification, genotypic and phenotypic clustering of Staphylococcus xylosus strains from dry sausages

AIMS

To ascertain the identification and typing of the Gram-positive, coagulase-negative cocci present in 'Salsiccia Sotto Sugna', an Italian artisanal sausage.

METHODS AND RESULTS

Fifty-one strains were isolated and genotypically identified by amplification of the 16S-23S rDNA intergenic region with universal primers. Most isolates were identified as Staphylococcus xylosus and one strain as Staph. condimenti. Isolates were clustered by numerical analysis of both RAPD (Random Amplified Polymorphic DNA) PCR profiles and physiological characters. Genotypic clustering allowed the separation of strains showing nitrate reduction and amino acid decarboxylase activities. Phenotypic clustering distinguished strains isolated at diverse ripening stages.

CONCLUSION

The predominance of Staph. xylosus in Italian dry sausages was confirmed. Genotypic similarities related to the possession of single phenotypic traits.

SIGNIFICANCE AND IMPACT OF THE STUDY

In this study, a rapid method of Staphylococcus and Kocuria species distinction was proposed. The suitability of RAPD PCR to discriminate strains of Staph. xylosus with technologically relevant activities was reported.

Development of the Specific and Random Amplification (SARA)-PCR for both species identification of enterococci and detection of the vanA gene

A rapid and reliable polymerase chain reaction (Specific and Random Amplification (SARA)-PCR) has been developed to identify enterococcal species and to detect the vanA gene in one single reaction. This technique was based on the use of the primer set previously designed to amplify a part of the vanA gene (Dutka-Malen et al., J. Clin. Microbiol., 33 (1995) 24-27). In the chosen low stringency conditions complex patterns were obtained, with a sharp band of approximately 700 bp in cases where the vanA gene was present. Discrimination at the species and strain level was achieved by applying the SARA-PCR assay to a collection of 55 enterococcal isolates and type strains. Simultaneously the vanA gene was detected in all strains showing high resistance to vancomycin.

Genomic DNA fingerprinting of Oenococcus oeni strains by pulsed-field gel electrophoresis and randomly amplified polymorphic DNA-PCR

Genetic diversity of 60 Oenococcus oeni strains from different wines was evaluated by numerical analysis of (i) pulsed-field gel electrophoresis (PFGE) patterns with endonuclease ApaI and (ii) randomly amplified polymorphic DNA (RAPD)-PCR fingerprints with four oligonucleotide primers. Sixty-two percent of the strains could be distinguished by PFGE, whereas most strains were identified by distinct RAPD-PCR profiles and associated according to the geographical origin. Because of its rapidity and reliability, RAPD-PCR appeared to be a suitable method for typing and monitoring O. oeni strains in winemaking.

Use of PCR-based methods for rapid differentiation of Lactobacillus delbrueckii subsp. bulgaricus and L. delbrueckii subsp. lactis

Two PCR-based methods, specific PCR and randomly amplified polymorphic DNA PCR (RAPD-PCR), were used for rapid and reliable differentiation of Lactobacillus delbrueckii subsp. bulgaricus and L. delbrueckii subsp. lactis. PCR with a single combination of primers which targeted the proline iminopeptidase (pepIP) gene of L. delbrueckii subsp. bulgaricus allowed amplification of genomic fragments specific for the two subspecies when either DNA from a single colony or cells extracted from dairy products were used. A numerical analysis of the RAPD-PCR patterns obtained with primer M13 gave results that were consistent with the results of specific PCR for all strains except L. delbrueckii subsp. delbrueckii LMG 6412(T), which clustered with L. delbrueckii subsp. lactis strains. In addition, RAPD-PCR performed with primer 1254 provided highly polymorphic profiles and thus was superior for distinguishing individual L. delbrueckii strains.

Genus- and species-specific PCR-based detection of dairy propionibacteria in environmental samples by using primers targeted to the genes encoding 16S rRNA

PCR assays with primers targeted to the genes encoding 16S rRNA were developed for detection of dairy propionibacteria. Propionibacterium thoenii specific oligonucleotide PT3 was selected after partial resequencing. Tests allowed the detection of less than 10 cells per reaction from milk and cheese and 10(2) cells per reaction from forage and soil.

Genetic and phenotypic diversity of Saccharomyces sensu stricto strains isolated from Amarone wine. Diversity of Saccharomyces strains from Amarone wine

Individual yeast strains belonging to the Saccharomyces sensu stricto complex were isolated from Amarone wine produced in four cellars of the Valpolicella area (Italy) and characterized by conventional physiological tests and by RAPD-PCR and mtDNA restriction assays. Thirteen out of 20 strains were classified as Saccharomyces cerevisiae (ex S. cerevisiae p.r. cerevisiae and p.r. bayanus) and the remaining as Saccharomyces bayanus (ex S. cerevisiae p.r. uvarum). RAPD-PCR method proved to be a fast and reliable tool for identification of Saccharomyces sensu stricto strains and also gave intraspecific differentiation. Restriction analysis of mtDNA permitted to distinguish S. cerevisiae and S. bayanus species and to discern polymorphism among S. cerevisiae isolates. The assessment of the phenotypic diversity within the isolates by gas-chromatographic analysis of secondary fermentation products was explored. Small quantities of isobutanol were produced by most of the strains and higher amounts by some S. cerevisiae strains with phenotypes Gal- and Mel-; all S. bayanus strains produced low amounts of amilyc alcohols. From this study it appears that each winery owns particular strains, with different genetic and biochemical characteristics, selected by specific environmental pressures during the Amarone winemaking process carried out at low temperature in presence of high sugar content.

Partial characterization and plasmid linkage of a non-proteinaceous antimicrobial compound in a Lactobacillus casei strain of vegetable origin

Lactobacillus casei IMPC LC34 of vegetable origin produces a non-proteinaceous inhibitory compound with a broad spectrum of activity towards Gram-positive and Gram-negative bacteria, including pathogens. The active substance, mainly produced in the stationary phase of growth, is insensitive to proteolytic enzymes, lipase and catalase, and is stable at 121 degrees C for 30 min. The inhibitory activity was detected either at 8 degrees C or at 37 degrees C. The active compound does not contain glucidic groups, is inactivated by Na-metaperiodate, and its molecular mass is between 2000 and 5000 Da. Plasmid curing experiments showed that both antimicrobial compound immunity and production determinants were encoded by an 8.8 kbp plasmid. The effectiveness of the active agent was verified on ready-to-use vegetables, using either the Lact. casei strain or its culture supernatant fluid as inoculant, compared with cured clone. The application potential of the Lact. casei strain or its culture supernatant fluid for assuring the microbiological safety of ready-to-use vegetables is discussed.

Identification and clustering of dairy propionibacteria by RAPD-PCR and CGE-REA methods

A total of 67 classical propionic acid bacteria (PAB) strains, 10 of which were from type culture collections and 57 from milk, typical Italian cheeses, acid whey and feed flour of different regions, were analysed by Randomly Amplified Polymorphic DNA (RAPD-PCR) and by Conventional Gel Electrophoresis Restriction Endonuclease Analysis (CGE-REA). The genotypic traits achieved using RAPD-PCR with three primers (OPL-01, OPL-02 and OPL-05) and SmaI CGE-REA patterns were compared by numerical analysis and allowed a clear distinction of four clusters corresponding to the currently described species of classical propionibacteria according to type and reference strains positions. No discrepancies exist in species recognition between the two methods; 36 isolates were identified as Propionibacterium freudenreichii, 15 as P. jensenii, four as P. acidipropionici and two as P. thoenii. Many differences, however, were observed in intraspecific clustering. Numerical comparison of RAPD-PCR profiles appeared to be a suitable method for highlighting the presence of particular phenotypic characters, while intraspecific differentiation obtained by CGE-REA analysis allowed association of strains at high similarity levels on the basis of their geographical origin.

Design and evaluation of malolactic enzyme gene targeted primers for rapid identification and detection of Oenococcus oeni in wine

Rapid identification and detection of Oenococcus oeni was achieved by species-specific PCR. Two primers flanking a 1025 bp region of the O. oeni gene encoding the malolactic enzyme were designed. The expected DNA amplificate was obtained only when purified DNA from O. oeni was used. The identity of PCR product was confirmed by nested PCR and restriction analysis. Within 8 h, 10(3) cfu ml-1 of oenococci were detected in fermenting grape must containing 10(7) yeast cells, whereas the detection limit in wine was 10(4) cfu ml-1. The rapidity and reliability of the PCR procedure established suggests that the method may be profitably applied in winery laboratories for quality control.

Lactobacillus curvatus subsp. curvatus subsp. nov. and Lactobacillus curvatus subsp. melibiosus subsp. nov. and Lactobacillus sake subsp. sake subsp. nov. and Lactobacillus sake subsp. carnosus subsp. nov., new subspecies of Lactobacillus curvatus Abo-Elnaga and Kandler 1965 and Lactobacillus sake Katagiri, Kitahara, and Fukami 1934 (Klein et al. 1996, emended descriptions), respectively

Lactobacillus curvatus and Lactobacillus sake are each genetically homogeneous species, as indicated by the high levels of DNA homology (> or = 76%) exhibited by strains of these taxa. However, the results of a numerical analysis of total soluble cell protein patterns and biochemical test data revealed that there are two phenotypic subgroups within L, curvatus and two phenotypic subgroups within L. sake. The overall randomly amplified polymorphic DNA (RAPD)-PCR band patterns obtained for the majority of L. curvatus strains corresponded well to the pattern obtained for the type strain of L. curvatus (strain DSM 20019). However, six strains of L. curvatus had different, but similar, RAPD-PCR profiles and grouped in a separate genetic cluster, which was linked to one of the clusters of L. sake strains. On the basis of these results, differences in biochemical and physiological characteristics, and total soluble cell protein profiles, we describe the subspecies L. curvatus subsp. curvatus subsp. nov. and L. curvatus subsp. melibiosus subsp. nov. for L. curvatus Abo-Elnaga and Kandler 1965 (Klein et al. 1996, emended description). Strains of L. sake grouped in two RAPD-PCR clusters, which was consistent with previous reports of phenotypic heterogeneity. Strains of Lactobacillus bavaricus, including type strain LMG 9844, clustered with the type strain of L. sake (strain NCFB 2714), indicating that these organisms belong to the same genetic group. We propose that strains of L. sake Katagiri, Kitahara, and Fukami 1934 (Klein et al. 1996, emended description) should be reclassified as members of L. sake subsp. sake subsp. nov. and L. sake subsp. carnosus subsp. nov. Strains of L. bavaricus are reclassified as members of L. sake subsp. sake, and the name L. bavaricus Stetter and Stetter 1980 is rejected.

Application of antimicrobial-producing lactic acid bacteria to control pathogens in ready-to-use vegetables

Five psychrotrophic strains of lactic acid bacteria (Lactobacillus casei, Lact. plantarum and Pediococcus spp.) were isolated from 22 samples of commercial salads. These strains were shown to inhibit Aeromonas hydrophila, Listeria monocytogenes, Salmonella typhimurium and Staphylococcus aureus on MRS agar, in salads and in juice prepared from vegetable salads. Lactobacillus casei IMPCLC34 was most effective in reducing total mesophilic bacteria and the coliform group; Aer. hydrophila, Salm. typhimurium and Staph. aureus disappeared after 6 d of storage, while the counts for L. monocytogenes remained constant. The potential application of antimicrobial-producing lactic acid bacteria as biopreservatives of ready-to-use vegetables is suggested.

Inhibitory effect of selected lactic acid bacteria on microflora associated with ready-to-use vegetables

The addition of selected lactic acid bacteria strains had a remarkable inhibitory effect on the growth dynamics of microflora associated with ready-to-use vegetables, during refrigerated storage. In particular, coliforms and enterococci were strongly reduced or eliminated from the products from the third day of storage. Lactobacillus casei strains proved more effective than pediococci. The use of lactic cultures able to produce bacteriocins and to grow at low temperatures could be a useful tool to preserve fresh vegetables and to ensure their microbiological safety.

Growth modelling of Listeria monocytogenes and Yersinia enterocolitica in food model systems and dairy products

The growth potential of Listeria monocytogenes, measured with a gaschromatographic method, was evaluated in model systems simulating dairy products in which NaCl concentration, pH and lipid concentration ranged from values corresponding to matured hard cheeses to some light cheeses and other dairy products. The growth data from the model systems, calculated on the basis of the polynomial models obtained, were compared with values observed for dairy products. Growth parameters of Yersinia enterocolitica in traditional and light cheeses were also available. The comparison between predicted and observed data suggested that individual or interactive effects of chemicophysical variables such as pH, salt and lipid concentration are not sufficient to predict the fate of L. monocytogenes in dairy products. Microstructural factors as well as the pH effect on water binding capacity of proteins could also be implicated.

Effect of weight reduction in moderately overweight patients on recorded ambulatory blood pressure and free cytosolic platelet calcium

Although platelet cytosolic calcium has been shown to decrease during pharmacological treatment of hypertension, there is no evidence that cytosolic calcium also falls during a nonpharmacological reduction in blood pressure. To provide such evidence, we examined prospectively the relation between platelet cytosolic calcium and ambulatory blood pressure during weight reduction in moderately overweight (body mass index [BMI] greater than 25), mildly hypertensive individuals. The experimental group (responders: BMI reduction greater than 5%) consisted of 19 patients who lost 8.5 +/- 2.9 kg (mean +/- SD, p less than 0.05) during a 10-week hypocaloric diet, whereas the control group (nonresponders: BMI reduction less than 5%) consisted of 12 patients who showed no relevant change in body weight (-2.0 +/- 1.3 kg) during the same period of time. The moderate weight loss of the responders decreased blood pressure by 14/5 mm Hg (p less than 0.05), as measured by ambulatory monitoring, which renders a placebo effect unlikely. This nonpharmacological reduction in blood pressure was accompanied by a proportional 11% decrease (p less than 0.05) in platelet cytosolic calcium and also by significant (p less than 0.05) decreases in plasma catecholamines and serum cholesterol. These findings establish the concept of a nonpharmacological reduction in free cytosolic platelet calcium in humans and add further evidence suggesting a link between intracellular calcium homeostasis and blood pressure regulation.

Ambulatory blood pressure monitoring in the elderly hypertensive patient

In this retrospective analysis, we assessed the usefulness of ambulatory blood pressure monitoring in the evaluation of elderly hypertensive patients. Thirty-eight untreated and 31 treated hypertensives aged 70 years or more had a systolic blood pressure greater than or equal to 160 mmHg and/or a diastolic blood pressure greater than or equal to 95 mmHg in the clinic. All 69 patients underwent blood pressure monitoring during their customary daily activities using a portable semi-automatic blood pressure recorder (Remier M2000). The mean of all blood pressures obtained with this device was taken as the ambulatory recorded blood pressure. Recorded blood pressures were greater than or equal to 160 mmHg systolic and greater than or equal to 90 mmHg diastolic in 17 untreated and 17 treated patients. In these patients, the introduction of antihypertensive therapy, or its modification, markedly reduced blood pressure during a 4-8 month follow-up. A further 21 untreated and 14 treated patients had recorded blood pressures of less than 160/90 mmHg. The treatment status of these patients was left unchanged for 4-8 months of follow-up. Nevertheless, office blood pressure in these groups, with no change in treatment, decreased significantly during the observation period. At the last visit to the outpatient clinic, there was no significant difference in blood pressure between the four subgroups of patients. Thus, ambulatory blood pressure monitoring appears to be useful in the elderly hypertensive patient in detecting those patients whose blood pressure is elevated only in the clinic. Blood pressure profiles obtained outside the clinic may therefore be useful in making therapeutic decisions in the aged hypertensive.

Identification of vaginal lactobacilli from asymptomatic women

In the present work, carried out by means of phenotypic and genotypic tests, it has been demonstrated that none of the vaginal lactobacilli isolated from asymptomatic women were genetically close to L. acidophilus ATCC 4356. Strains of homofermentative lactobacilli were identified as Lactobacillus gasseri, L. jensenii and L. crispatus, while in the heterofermentative only one strain was classified as L. fermentum. Moreover a genetically homologous group of heterofermentative lactobacilli, that could represent a new species, were evidenced.